Hello, World!
The obligatory "Hello, World!", but it's a pretty cool design and implementation that you will really love. That's because it's a service that demonstrates the reactive platform components.
The
xoom-helloworld example is a pinned repository on our GitHub VLINGO organization. To use to it learn, first clone the repository and build the project. Open a console/command window so you can build the xoom-helloworld artifact and start it by executing the built jar file.Note that snapshot artifacts are hosted on GitHub, which requires credentials to be provided to Maven by way of it's
~/.m2/settings.xml. This is explained in more detail and with an example here.$ git clone https://github.com/vlingo/xoom-helloworld.git
...
$ cd xoom-helloworld
$ mvn package
...
java -jar target/xoom-helloworld-withdeps.jar
...
$
The above
java command executes the jar on the default port 18080. If you would like to use a different port, you must provide it on the command line. This command uses port 8080.$ java -jar target/xoom-helloworld.jar 8080
The following examples assume that you have started the service with the default port,
18080.There are two resources, each with multiple endpoints. These are discussed next.
The first resource is used to get
"Hello, World!" and similar messages.You may
curl with GET methods on the following resources.$ curl -i -X GET http://localhost:18080/hello
The above
curl responds with 200 OK and the content body entity "Hello, World!"You may also provide a path parameter to indicate to whom the service should say
"Hello". The second example responds with 200 OK and the content body entity "Hello, Me!"$ curl -i -X GET http://localhost:18080/hello/Me
In this Hello resource example there is only one component involved,
io.vlingo.xoom.hello.infra.resource.HelloResource.The second resource is a bit more involved, and is used to maintain any number of
Greeting messages. These greetings have the following data associated with them.id: a unique identitymessage: a text messagemessageChangedCount: the number of times the message text has changed since first being defineddescription: a text description of the messagedescriptionChangedCount: the number of times the description text has changed since first being defined
The first operation used is to define a new
Greeting. To do so you POST a JSON object to the /greetings URI.$ curl -i -X POST -H "Content-Type: application/json" -d '{"id":"","message":"Hey","messageChangedCount":"0","description":"Says Hey","descriptionChangedCount":"0" }' http://localhost:18080/greetings
The resource will respond with (only the id could be different):
HTTP/1.1 201 Created
Location: /greetings/242
Content-Length: 105
{"id":"242","message":"Hey","messageChangedCount":0,"description":"Says Hey","descriptionChangedCount":0}
Following this you may query the new
Greeting. The Location of the new Greeting resource is /greetings/{someId}. Let's GET that resource.$ curl -i -X GET http://localhost:18080/greetings/242
You should see the following:
HTTP/1.1 200 OK
Content-Length: 105
{"id":"242","message":"Hey","messageChangedCount":0,"description":"Says Hey","descriptionChangedCount":0}
Next
PATCH the Greeting resource's message.$ curl -i -X PATCH -H "Content-Type: application/json" -d '{"value":"Yo"}' http://localhost:18080/greetings/242/message
The resource responds with the following. Note that the
message has changed to "Yo", and the messageChangedCount is now 1. Also notice that the description and the descriptionChangedCount remain unchanged.HTTP/1.1 200 OK
Content-Length: 104
{"id":"242","message":"Yo","messageChangedCount":1,"description":"Says Hey","descriptionChangedCount":0}
Next
PATCH the Greeting resource's description.$ curl -i -X PATCH -H "Content-Type: application/json" -d '{"value":"Says Yo"}' http://localhost:18080/greetings/242/description
The resource responds with the following. Note that the
description has changed to "Says Yo", and the descriptionChangedCount is now 1.HTTP/1.1 200 OK
Content-Length: 103
{"id":"242","message":"Yo","messageChangedCount":1,"description":"Says Yo","descriptionChangedCount":1}
Now both the
message and the description and the corresponding counts have all changed.In this
Greeting resource example there are various component sets involved. See the following source code.io.vlingo.xoom.hello.Bootstrap
io.vlingo.xoom.hello.resource.GreetingResource
io.vlingo.xoom.hello.model.Greeting
io.vlingo.xoom.hello.model.GreetingEntity
io.vlingo.xoom.hello.model.GreetingState
io.vlingo.xoom.hello.infra.persistence.GreetingProjectionActor
io.vlingo.xoom.hello.infra.persistence.Queries
io.vlingo.xoom.hello.infra.persistence.QueriesActor
io.vlingo.xoom.hello.infra.persistence.* - lower-level persistence setup and storage access
Documentation for the above components is found in the following links.
Last modified 6mo ago